Hydraulic properties of the Paskapoo Formation in west-central Alberta

Abstract

In an effort to better understand the hydraulic properties of the Paskapoo Formation, hydraulic conductivity and porosity were evaluated for a region in west-central Alberta. Whereas previous studies have focused mainly on sandstone units in the lower portion of the Paskapoo Formation, in southern and central parts of the province, this study focuses on the middle to upper portions. Hydraulic conductivity values were determined by air permeametry for seven drill cores from the area between Hinton and Fox Creek, Alberta. Thin-section petrology and porosity analyses using photomicrographs were also conducted for three of the seven drill cores. Results confirm previous findings that the Paskapoo Formation has heterogeneous hydraulic properties, with horizontal hydraulic conductivity values ranging from 10−10 to 10−5 m/s (determined by air permeametry) and porosity values ranging from 0.02% to 15.3%. The first measurements for the upper sandstone units are provided (1.1 × 10−9 – 2.6 × 10−5 m/s and 0.08%–15.3%) and numerous measurements of the middle siltstone–mudstone unit (1.1 × 10−10 – 4.9 × 10−8 m/s and 0.02%–1.8%) for the northwestern portion of the Paskapoo Formation. Qualitative petrologic analysis suggests that the degree of cementation, rather than grain size, is the dominant control on the hydraulic properties of this portion of the formation. This study determined primary hydraulic properties for both the highly conductive units often considered as aquifers and the low-conductivity units considered as aquitards or confining layers. When combined with previous findings, this study helps expand the understanding of the Paskapoo Formation and provides critical data for assessing groundwater resources.